It's quite possible you have missed the very handy "Unbilled Costs by Job" report in QuickBooks.

Located under Reports > Jobs Time and Mileage, this report provides some instant feedback to you concerning expenses your business has incurred that have not yet been billed back to your customers.

Here is a screen shot (click on it for a larger view) with more detail:

This report provides a quick recap of all unbilled expenses for all jobs. Like other QuickBooks reports, you can add or remove various columns to it and memorize it for future use.

The Unbilled Costs by Job Report can be found in the Pro, Premier and Enterprise versions of QuickBooks for Windows.

BONUS TIP:

if you need to see this report for one or a select handful of jobs instead of all of them, click the Modify Report button in the top left portion of the report screen, then the Filters tab, then the Name filter, then Multiple Names from the top of the filter list. From there, simply select the names you would like to appear on the report!